412 THE ANATOMY OF VEETEBRATED ANIMALS. 



have three roots in the upper jaw, two in the lower. The 

 crowns of the middle molars, above, have four cusps, and an 

 oblique ridge which extends from the antero-external to the 

 postero-iaternal cusp ; and those of the middle molar, below, 

 have five cusps, -as in Man. The crown of the anterior premo- 

 lar in the lower jaw is pointed, and has a long, sharp, ob- 

 lique anterior edge as in the Cynomorpha. 



In the Gibbons, the permanent canine emerges contem- 

 poraneously with, or before, the last molar ; but, in the other 

 Anthropomorpha, the last permanent canine is cut, ordinarily, 

 only after the appearance of the last molar. 



In the Orang the circumvallate papillae of the tongue are 

 arranged in a V, as in Man. In the Chimpanzee they are dis- 

 posed like a T, with the top turned forward. The Chimpanzee 

 and the Siamang have a uvula, but the Orang has none. 

 The stomach of the Chimpanzee is very like that of Man ; but 

 in the Orang the organ is more elongated, with a round car- 

 diac and more tubular pyloric portion. An appendix vermi- 

 formis is found in the OEeoum of all four genera. In the 

 Chimpanzee and Gorilla, the origin of the great arteries from 

 the arch of the aorta takes place as in Man. In the Orang, 

 they are sometimes disposed as in Man ; while in other speci- 

 mens the left carotid comes off from the innominata, and only 

 the subclavian of the left side arises directly from the aorta. 

 In Sylobates, the latter arrangement appears to obtain. 



The kidney has only a single papilla in Sylobates and 

 Pithecus. 



Only one species of Sylobates, namely, the Siamang, is 

 known to possess a laryngeal sac. This is globular, and com- 

 municates by two apertures, situated in the thyro-hyoid mem- 

 brane, with the larynx. In the Orang, Chimpanzee, and Go- 

 rilla, enormous air-sacs result from the dilatation of the lateral 

 ventricles of the larynx. These dilatations extend down, in 

 front of the throat, on to the thorax and even into the axillaa, 

 and sometimes open into one another in the middle line. 



In the adult male Chimpanzee the penis is small and slen- 

 der, and terminates in a narrow and elongated glans. The 

 testes are very large, and the communication between the 

 tunica vaginalis and the peritonreum is completely closed. 

 The glans penis of the Gorilla is button-shaped. In the 

 Orang it is cylindrical, and the testes are situated close to the 

 inguinal canal, which has been found open on one side, and 

 closerl on the other. An os penis is developed in the males. 

 The females have the clitoris large, and the uterus, which 



